Seismic and well log data is traditionally used to define and estimate the subsurface structure of reservoir bodies or target sites. Seismic and well log data can provide porosity, permeability, fluid and gas saturation data, as well as other reservoir properties, which is measured and computed at a high level of accuracy. These data are often plotted using a computer simulation such that the regions of interest are defined relative to various features, such as surface topography or reservoir production infrastructure. Based upon two-dimensional or three-dimensional plots of seismic data, a user will assess where to appropriately locate one or more surface well platforms to adequately access these subsurface regions using a variety of drilling methods. With advances in directional drilling, and subsurface positioning of these directional drilling tools, a single platform may be located to intersect a plurality of target sites. To date, the location of a platform is selected by an experienced user familiar with the constraints of directional drilling apparatus. For example, an experienced user would recognize the minimum turning radius (dogleg severity) of a directional drilling tool while computing the well paths from a surface platform to one or more target areas. Additionally, because the number of target areas identified using seismic data may be large, there exist numerous possible combinations of proposed well paths leading from a surface platform to one or more target areas. Each of these proposed pathways have a cost associated with the production of the well path, as well as a degree of difficulty that may be influenced by various factors such as topography or earth composition. Additionally, sub-optimal selection of well pathways, platform locations, or the total number of wells may have long lasting detrimental effects.
Conventional well planning techniques may include the use of computer simulations wherein a static computer model is generated which includes each proposed well. Following the location of a well within the static model various existing reservoir simulation techniques may be utilized to explore the proposed well location. This process is continuously repeated, with the introduction of additional well locations until a proposed “best” solution is generated. To date this is a highly unpredictable method of platform location, as the generated data set on which long term decisions is based is unnecessarily small. Furthermore, such a computational approach is processor intensive, and may take a long period of time for results to be generated.
Accordingly, a need exists to automate the optimization of multi-well trajectories leading from a surface platform to a variety of target areas.